<!DOCTYPE html>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<!-- 引入外部的js脚本 -->
<script src="./demo.js"></script>



<body>
    
</body>

<!-- 内部脚本 -->
<script>
   //js语言
   alert("弹出来呀！");
   confirm("确定吗？");

</script>

</html>